Method for converting hydrocarbons



c 20, 1931- c. J. PRATT METHOD FOR CONVERTING HYDROCARBONS Filed Nov.

J71 2 Q72 to 1*. Clifton J 1 210 ft,

4 fig Patented Oct. 20, 1931 rename CLIFTON J'. PRATT, OF TULSA, OKLAHOMA, ASSIGNOIR, TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA.

METHOD FOR CONVERTING HYDROCARBONS Application filed November 4, 1926. Serial No. 146,116.

The present invention relates more particularly to improvements in a method and apparatus for converting heavy or low boiling point range hydrocarbons into lighter hydrocarbons of higher boiling point range.

The invention in its more specific embodiment is directed toward the step of arresting or preventing further cracking or conversion taking place in a dephlegmator, which is accomplished bysubjecting the vapors in their passage from a vapor separating zone to said dephlegmator, to a cooling action, thus reducing the temperature of said vapors to a point below the temperature at which further conversion would take place.

This step is preferably accomplished by subjecting the vapors to indirect contact with a cooling liquid, and as a feature of the operation t s cooling liquid may comprise either the charging stock or the cooling liquid which is normally introduced under present practice to the dephlegmator.

As a further feature of the present invention, any solid particles which may be entrained with the vapors will be stripped from said vapors simultaneously with said coolin action.

any advantages and objectsof the present invention will be hereinafter more particularly brought out.

In the drawing, the single figure is a diagrammatic bide elevational view partly in vertical section, of an apparatus of the tube and drum type.

Referring more particularly to the drawing, 1 designates an inlet line in which is interposed a valve 2 discharging into the pump 3. Line 1 receives charging stock from any suitable source of supply, such as a storage tank or the like. The pump 3 forces the charging stock through they line 4 and meter 5 which line 4 divides into two branches 6 and 7 which may be controlled by the throttle valves 8 and 9. The branch 6 communicates with inlet line 10 which may be controlled by the valve 11, which line 10 may communicate with the heatin tubes 12 mounted in the furnace 13. Thls furnace 13 is illustrated as being of the side fired type, heated by'means of burners 14, but

it is to be understood that this showing is merely illustrative, and any type of furnace may be utilized, which is found desirable.

When the valve 9 is closed and valve 8 opened, the charging stock is fed directly through the. branch 6 and line 10 to the heating coils 12. It may be desirable to split the feed, in which case both of the valves 8 and 9 are partly opened, or all of the charging stock may be fed through the line 7. Interposed in the line 7 is a second valve 15, the line itself terminating in the interior of the dephlegmator 16, provided with baffles illus- I trated diagrammatically at 17. Reflux condensate and the unvaporized charging stock will collect in the reflux leg 18, and may be returned through line 19 to the heating tubes 12 for further treatment, or all or any portion of the reflux and /or charging stock may be diverted through the line 20 controlled by the line 21. A valve 22 may be interposed in the line 19.

chamber 28. This chamber is preferably ex-' ternally unheated, and insulated as shown at 29.

It is to be understood that the chamber may or may not be externally heated. It may be provided with the clean-out openings 30 at its top and bottom, and it may be sup ported on the concrete pillars 31. This chamber may be of any height and instead .Of being vertically disposed as shown, may be horizontally disposed if desired. Separation of the vapors takes place within the chamber 28, said vapors dischargin'gthrough the vapor outlet pipe 32 in which may be interposed the valve 33. Unvaporized residue may be drawn ofii' through any one or more of this purpose, there is provided a branch line tubes 40.. This charging stock may exit from tated therein. have been entrained with the vapors, and are the residue drawoff lines illustrated diagrammatically at 34 in which may be inter-' posed valves 35, the lines 34 communicating with a suitable header 36. It is understood that there may be any number of these drawolf lines 34 disposed throughout the height of the chamber 28, the function of which is to permit the discharge of unvaporized residue when a body of precipitated carbon has built up and clogged the drawoff line below.

As a feature of the present invention, the

vapors exiting from the chamber 28 and passing through the line 32 are cooled materially and reduced in temperature by being forced to pass through a cooler designated as a 'whole 37 This cooler may take any desired form, for instance, it may take the form as shown, of a heat interchanger having the upper header 38, lower header 39 and communicating upright tubes 40. The space surrounding the tubes40 in this" instance, comprises the space through which the cooling 1i uid may be passed.

f it is desired to utilize a liquid from an external source, which is notto be introduced into the system, this liquid may be introduced through the line 41 controlled by valve 42 .and discharged through the line 43 controlled by the valve 44, passing in indirect contact with the vaporsi'lowing downwardly through the upright pipes 40.

The extent to which 't is desired to cool the vapors is carefully controlled and regulated by the temperature of the cooling medium and the ratio of the length of travel of the vapors to the amount of cooling space. Any vapors which condense may be withdrawn through the line 45 controlled by the valve 46, or by closing said valve may be introduced directly into the lower portion of the dephlegmator 16 through pipe 47 in which is interposed the valve 48, which pipe 47 is the transfer pipe for introducing the vapors from the cooler 37 to the dephlegmator 16. The upper and lower headers 38 and 39 may be closed by the movable caps 49 and 50 respectively, the arrangement being such that the tubes may be easily cleaned if desired. In addition to this the lower cap 50 may be removed to permit the removal of any solid particles which may be precipi- These solid particles may stripped from said vapors in the cooler 37 simultaneously with said cooling.

As another feature of the present invention,'the valves'42 and 44 may be closed and the cooling liquid utilized may comprise regulated portions of the charging stock. For

51 having a valve 52' interposed therein, which communicates with the line 7, and also communicates with the space between the upper and lower headers 38 surrounding the the cooler 37 through the line 53 in which may be interposed the valve 54, again joining the pipe 7 and introducing said charging stock into the upper end of the dephlegmator 16 as shown.

In this way, regulated portions of the charging stock serve to cool the vapors prior to dephlegmation, by being brought into indirect contact therewith, and subsequently said preheated portions of the charging stock are introduced into the dephlegmator where they are brought into direct physical contact with thewapors remaining uncondensed.

It is thought that only a brief description of the step of dephlegmation will be sufficient, the vapors passing upwardly in aback and forth movement throughout the height of the dephlegmator, the temperature being so controlled that the heavier ends are condensed. The vapors remaining uncondensed after passing through the dephlegmator pass out through the vapor outlet pipe55 in which may be interposed-valve 56 being condensed in the condenser coil 57 and collected as distillate in the receiver 58, which may be equipped with the usual sight glass gauge 59, pressure gauge 60, incondensable gas relief valve 61, and liquid drawofi valve-62.

As a feature of the present invention, in some instances it may be found desirable to return regulated quantities of the distillate collected in the receiver 58 to the dephlegmator for cooling purposes. Simultaneously,

this distillate may be utilized as the cooling medium for reducing the temperature of the vapors directed to the dephlegmator. For this purpose, the pipe 63 in which is interposed the valve 64.may be provided, it being understood that the pipe 63 receives the distillate either from the receiver 58.or from any suitable source. The distillate passing through the pump 65 is forced through the line 66 in which may be interposed valves 67 and 68, discharging said distillate into the upper end of the dephlegmator 16. A branch 69 controlled by the valve 70 communicates with the branch '51 for the purpose of diverting regulated portions of this pressure distillate through the cooler 37, and a similar branch 71 controlled by the valve 72 communicates with the branch 53 and also with the main line 66 as shown.

The method of operation should be apparent from the foregoing description. The entire apparatus is adapted to be operated under any desirable superatmospheric pressure from three to several hundred pounds more or less, or under atmospheric pressure, or under a vacuum, or various parts of the system may be maintained under differential pressures Within the scope of the present invention.

The proper temperature to which to heat the oil to secure optimum results in conversion, will depend upon the type of charging aeaaoea I around 825 F. (ll-aching continues at this temperature, and ifthe-vapors were permit" ted to enter the dephlegmator at such a temperature the continuous cracking would cause carbon to be formed and precipitated in the lower pans or bafies 17, thus clogging said pans and necessitating their cleaning or removal. By passing said vapors through the cooler37, they may be cooled to say 600 F. more or less, before they enter the dephlegmator, which will arrest and prevent any further cracking. The temperature conditions of the dephlegmator 16 may be so controlled as to condense all fractions having a boiling point above say, 437 F. more or less. It is to be understood that these figures are merely illustrative, and the temperatures may Vary widely within the scope of the in vention. It is to be emphasized however, that it is preferable to cool the vapors below a cracking temperature.

By carefully regulating and controlling I the temperature of the vapors permitted to enter the lower end of the de hlegmator, any tendency to continued crac ing. and subse quent deposition of coke in the dephlegmator is prevented; i

I claim as my invention:

1. A hydrocarbon. oil cracking process which comprises continuously passing the oil 7 through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated Oll into an enlarged reaction zone malntamed under cracking conditions of temperature and pressure process, then introducing the'vapors and said charging oil to the lower and upper portions respectively of a dephlegmating zone, and passing them in countercurrent heat exchange relation therein to condense heavier fractions .2. A. hydrocarbon oil cracking process which comprises continuously passing the oil through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated oil into an enlarged reaction zone maintained under cracking. conditions of temperature and pressure and separating the same therein into vapors and unvaporized (uh-separately re moving the vapors and unvaporized oil from said reaction zone and passing the former to a dephlegmating zone, simultaneouslyadvancing a stream of charging oil for the process toward said dephlegmating zone, diverting a portion of said stream into indirect heat exchange relation with said vapors prior to introduction of the latter to said dephlegmating zone and cooling the vapors to below cracking temperature but not substantially' below 600 F, then introducingthe vapors into the lower portion of said dephlegmating zone,.introducing the remaining portion of said dephlegmating zone, in-

troducing the remaining portion of the charging oil stream and the diverted portion thereof into the upper portion of said dophlegmating zone andjn direct contact with the vapors therein thereby condensing insuficient-ly cracked fractions of the vapors as reflux condensate, removing admixed reflux condensate and unvaporlzedcharging oil from the lower portion of said dephlegmating zone and supplying the same to said heating zone, and finally condensing the de'phlegmated vapors,

onrr'ron J. rna'rr.

CERTIFICATE OF coRREcTIoN.

Patent No. 1,827,908. October 20, 1931.

CLIFTON J. PRATT.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, lines 84 and 85, claim 2, strike out the words and comma "introducing the remaining portion of said dephlegmating zone,"; and that the said Letters Patent should be read wit/ this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of January, A. D. 1934.

i. M. Hopkins (Seat) Acting Commissioner of Patents. 

